What was found
MCN - MAJOR REPAIR - DURING C-17 CHECK 7 EACH .25 INCH CRACKS WERE FOUND ON FUSELAGE INTERIOR SKIN AT FASTENER HOLES ON LOWER ROW LAP SEAM STR 4 LT, BETWEEN BS 500B+9 AND BS 500B+19. UPON BOEING REQUEST TO EXTEND THE INSPECTION 1 EACH ADDITIONAL CRACK INDICATION WAS DETECTED AT BS 500A+13. MAINTENANCE TRIMMED OUT CRACKS ON SKIN AT STR 4 LT, BETWEEN BS 500A+13 AND BS 500B+19; FABRICATED A REPAIR DOUBLER, TRIPLER, 2 EACH FILLERS, AND 4 EACH INTERNAL DOUBLERS; INSTALLED REPAIR PARTS FROM BS 500A+10 TO 500C+2 IAW ER 03-5300-03155-TB2.